Methods and apparatuses for preheated interval welding

ABSTRACT

Preheated interval welding methods for welding a weld material to a substrate material can include preheating the substrate material to a preheat temperature less than a solidus temperature of the substrate material, melting the weld material to produce molten weld material at a melting distance away from the substrate material, and applying the molten weld material in a plurality of intervals to the substrate material.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to welding and, moreparticularly, repair welding for high temperature performance alloys.

Metal and alloy parts may experience various wear instances or patternsin material as a result of application fatigue such as cracking,wearing, abrasions, erosion or any other act that may cause the removalor wear of substrate material. To replace the loss in material andrepair the part, various forms of welding can be used to bond new weldmaterial to the original substrate material. Such welding can includeheating the substrate material (i.e., the part being repaired),contacting the weld material to the substrate material, and thenapplying additional heat or energy to the weld material so that the weldmaterial melts to become liquidus and can thereby bond with thesubstrate material. However, some materials, such as nickel basedsuperalloys that can be used in high temperature applications such as inhot gas path components in gas turbines (e.g., buckets), can crackand/or be less susceptible to forming strong bonds with weld material ifwelded while at a non-elevated temperature, such as at room temperature,and/or using non-matching weld material.

Welds may therefore be performed by preheating substrate materials to anelevated temperature prior to welding. However, the constant additionalheat or energy used during welding to actually melt the weld materialcan also radiate to the substrate material and cause an even furtherincrease in the substrate material's temperature such as to a pointabove its solidus or liquidus. Such an increase may then result inslumping, melting or other changes to the microstructure that can reducethe substrate material's physical properties such as strength and/ortoughness.

Accordingly, alternative welding methods and apparatuses would bedesirable in the art.

BRIEF DESCRIPTION OF THE INVENTION

In one embodiment, a preheated interval welding method for welding aweld material to a substrate material is disclosed. The preheatedinterval welding method includes preheating the substrate material to apreheat temperature less than a solidus temperature of the substratematerial, melting the weld material to produce molten weld material at amelting distance away from the substrate material, and applying themolten weld material in a plurality of intervals to the substratematerial.

In another embodiment, another preheated interval welding method forwelding a weld material to a substrate material is disclosed. Thepreheated interval welding method includes disposing a welding apparatusadjacent a substrate material, preheating the substrate material to apreheat temperature less than its solidus temperature, and transitioningthe welding apparatus element away from the substrate material andadjacent to the weld material. The method further includes melting theweld material to produce molten weld material and applying the moltenweld material in a plurality of intervals to the substrate material.

In yet another embodiment, a preheated interval welding system forpreheating a substrate material and applying a weld material isdisclosed. The preheated interval welding system includes a preheatingapparatus that preheats a repair surface of the substrate material to apreheat temperature and a welding apparatus that melts the weld materialinto molten weld material and applies the molten weld material to therepair surface in a plurality of intervals.

These and additional features provided by the embodiments discussedherein will be more fully understood in view of the following detaileddescription, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments set forth in the drawings are illustrative and exemplaryin nature and not intended to limit the inventions defined by theclaims. The following detailed description of the illustrativeembodiments can be understood when read in conjunction with thefollowing drawings, where like structure is indicated with likereference numerals and in which:

FIG. 1 is an exemplary preheated interval welding method according toone or more embodiments shown or described herein;

FIG. 2 is a schematic illustration of a preheated interval weldingsystem preheating a substrate according to one or more embodiments shownor described herein;

FIG. 3 is a schematic illustration of the preheated interval weldingsystem of FIG. 2 melting a weld material according to one or moreembodiments shown or described herein;

FIG. 4 is a schematic illustration of a preheated interval weldingsystem comprising two welding apparatuses that is preheating a substrateaccording to one or more embodiments shown or described herein; and

FIG. 5 is a schematic illustration of the preheated interval weldingsystem of FIG. 4 melting a weld material according to one or moreembodiments shown or described herein.

DETAILED DESCRIPTION OF THE INVENTION

Preheated interval welding methods disclosed herein generally comprisefirst preheating a substrate material to a preheat temperatureapproaching its solidus temperature. Weld material is then melted andapplied to the substrate material in a plurality of intervals. Theinterval-regimented application of weld material to the preheatedsubstrate material can allow for the reduction in temperaturedifferential between the two materials while further controlling theamount of excess heat applied to the substrate material around the weld.

With reference to FIGS. 1-3, an exemplary preheated interval weldingmethod 1 is illustrated that can be incorporated into various weldingsystems such as the exemplary preheated interval welding system 100illustrated in FIGS. 2 and 3.

As illustrated in FIGS. 2 and 3, the exemplary preheated intervalwelding system 100 may generally comprise a substrate material 110 thatis to have weld material 120 applied to it at one or more locations. Thesubstrate material 110 can comprise any type of material that can haveweld material 120 applied (i.e., contacted and subsequently bonded) toit at one or more locations. For example, the substrate material 110 maycomprise any metal, alloy, or other material that is capable of bondingwith a weld material 120 when the weld material 120 is in a liquidusstate from an application of energy such as heat. In some exemplaryembodiments, the substrate material 110 may comprise a nickel basedsuperalloy such as those used gas turbines for hot gas pathapplications.

The substrate material 110 may comprise any dimensions and geometry thatallow for a weld location to be preheated and then allow for theapplication of weld material 120. For example, in some embodiments, suchas that illustrated in FIGS. 2 and 3, the substrate material 110 maycomprise a relatively flat repair surface 111 with a void 112. The void112 may be present from various application fatigue, such as cracking,wearing, abrasions, erosion or any other act that may cause the removalor wear of substrate material 110. In other embodiments, the substratematerial 110 may comprise curves, corners, arms, joints or any othertype of shape such as those that may be present in a bucket for a gasturbine.

The exemplary preheated interval welding system 100 further comprises aweld material 120 that is to be welded onto the substrate material 110.The weld material 120 can comprise any material that can be heated to astate above its liquidus temperature such that it melts and can beapplied to the substrate material 110 in a plurality of intervals aswill become appreciated herein. In some embodiments, the weld material120 can comprise the same or similar material as the substrate material110. Such embodiments may allow for less shrinkage, cracking or otherperformance defects by having the substrate material 110 and the weldmaterial 120 possess the same or similar physical characteristics. Suchan embodiment can provide a closer match of physical properties betweenthe substrate material 110 and the weld material 120 to potentiallyallow for increased and more predictable performance.

Similar to the substrate material 110, the weld material 120 maycomprise any dimensions and geometry that allow for the weld material120 to be heated to a temperature greater than its liquidus temperaturesuch that molten weld material 121 can be applied in a plurality ofintervals to the substrate material 110. For example, in someembodiments, such as that illustrated in FIGS. 1 and 2, the weldmaterial 120 may comprise a long wire that can be unspooled and fed to alocation that is proximate the substrate material 110. In otherembodiments, the weld material 120 may comprise other configurationssuch as pellets, rods, blocks, ingots or any other size and/or shape.

Still referring to FIGS. 2 and 3, the exemplary preheated intervalwelding system 100 additionally comprises a welding apparatus 130. Thewelding apparatus 130 can comprise any apparatus that can apply enoughenergy (e.g., heat) to a weld material 120 to heat the weld material 120above its liquidus temperature so that it can be welded to the substratematerial 110. For example, in some embodiments, such as that illustratedin FIGS. 2 and 3, the welding apparatus 130 can comprise an inductionwelding apparatus comprising a power supply 131 connected to aninduction coil 132 via an electrical connection 133. In suchembodiments, the power supply 131 can provide an electric current to theinduction coil 132 through the electrical connection 133. When theelectric current is provided to the induction coil 132, the inductioncoil 132 produces an electromagnetic field to heat the neighboring workpiece through resistive heating from the electromagnetic induction. Itshould be appreciated that while the welding apparatus 130 isexemplarily illustrated as an induction welding apparatus, the weldingapparatus 130 may alternatively comprise any other type of weldingapparatus 130 such as, for example, an arc welding apparatus (e.g., TIGwelding), gas welding apparatus (e.g., oxyacetylene welding), energybeam welding apparatus (e.g., laser beam welding) and/or any otheralternative welding apparatus capable of heating the weld material 120above its liquidus temperature.

In some embodiments, such as that illustrated in FIGS. 2 and 3, theexemplary preheated interval welding system 100 may use the same weldingapparatus 130 to both melt the weld material 120 and preheat thesubstrate material 110 as will become appreciated herein. However, inalternative or additional embodiments, such as that illustrated in FIGS.4 and 5, the exemplary preheated interval welding system 100 may furthercomprise a separate preheating apparatus 140 that is used to preheat thesubstrate material 110. The preheating apparatus 140 can comprise anyapparatus operable to preheat an area of the substrate material 110(such as a void 112) that will have molten weld material 121 applied toit. For example, in some embodiments, such as that illustrated in FIGS.4 and 5, the preheating apparatus 140 may similarly comprise aninduction welding apparatus comprising a power supply 141 connected toan induction coil 142 via an electrical connection 143. In such anembodiment, the induction coil 142 can be placed adjacent the repairsurface 111 when the preheating apparatus 140 is preheating thesubstrate material 110 and transitioned away from the repair surface 111when not preheating the substrate material 110 as will becomeappreciated herein. In some embodiments, the preheating apparatus 140may comprise alternative and/or additional apparatuses to preheat thesubstrate material 110 including, for example, ovens, torches, lasers,other weld devices, or any other apparatus suitable to preheat an areaof the substrate material 110.

Referring now to FIGS. 1-3, the preheated interval welding method 1 canbe incorporated into various preheated interval welding systems 100 suchas those discussed above. The preheated interval welding method 1generally first comprises preheating the substrate material 110 in step10 and melting the weld material 120 in step 20.

Preheating the substrate material 110 in step 10 comprises heating thearea of the substrate material 110 where the weld material 120 is to beadded (e.g., a void 112 in the repair surface 111 of the substratematerial 110) to a preheat temperature. The preheat temperature cancomprise any temperature above room temperature such as a temperaturethat approaches the solidus temperature of the substrate material 110.

The substrate material 110 can be preheated using any availablepreheating apparatus 140 that is capable of heating an area of thesubstrate material 110 to the preheat temperature. As discussed above,in some embodiments (e.g., the embodiment illustrated in FIGS. 2 and 3),the welding apparatus 130 that is to be utilized to melt the weldmaterial 120 in step 20 may also be utilized to preheat the substratematerial 110 in step 10 (i.e., the welding apparatus 130 comprises thepreheating apparatus 140. For example, as illustrated in the preheatedinterval welding method 1 shown in FIG. 1, and with reference to thepreheated interval welding system 100 illustrated in FIGS. 2 and 3,preheating the substrate material 110 in step 10 may comprise firstdisposing the welding apparatus 130 adjacent the substrate material 110in step 11. Disposing the welding apparatus 130 adjacent to thesubstrate material 110 in step 11 can comprise disposing the heatingportion of the welding apparatus 130 (for example the induction coil 132for an induction welding apparatus as illustrated in FIGS. 2 and 3) inclose enough proximity to the to-be welded area of the substratematerial 110 to allow for its heating. In particular, where thesubstrate material 110 comprises a void 112 in the repair surface 111 asillustrated, then the induction coil 132 or other analogous part of thewelding apparatus 130 can be placed proximate the void 112.

Heat/energy may then be applied in step 12 to the substrate material110. For example, where the welding apparatus 130 comprises an inductionwelding apparatus, the electrical current from the power supply 131 canbe initiated such that the electromagnetic field from the induction coil132 creates resistive heating from the electromagnetic induction. Thepower supply 131 can be monitored and adjusted to heat the substratematerial 110 to the preheat temperature such as one that approaches butdoes not exceed the substrate material's 110 solidus temperature.

In some embodiments, the temperature of the substrate material 110 maybe monitored via one or more temperature sensors such as thermocouples,pyrometers thermometers and/or any other appropriate device. Feedbackfrom the one or more temperature sensors can be utilized to control theamount of heat and/or energy applied to the substrate material 110 suchthat its elevated preheat temperature is controlled. For example, suchfeedback can be utilized to control the amount of power to the weldingapparatus 130 (or other preheating apparatus 140), the distance betweenthe substrate material 110 and the welding apparatus 130, or any othervariable that may affect the temperature of the substrate material 110.

Preheating the substrate material 110 in step 10 may optionally furthercomprise transitioning the preheating apparatus 140 away from thesubstrate material 110 in step 13 to stop or limit the amount of heatapplied to the substrate material 110. For example, where the preheatingapparatus 140 would obstruct the application of the weld material 120,and/or where the continuous presence of the preheating apparatus 140would cause a continuous rise in temperature of the substrate material110, then the preheating apparatus 140 may be transitioned away from thesubstrate material 110 to better allow for the subsequent application ofmolten weld material 121 and/or limit the amount of preheating of thesubstrate material 110. Alternatively, where the physical presence ofthe preheating apparatus 140 does not interfere with the subsequentapplication of molten weld material 121 and the preheat temperature canstill be controlled with its continuous presence, the preheatingapparatus 140 may optionally remain adjacent the substrate material 110throughout welding to maintain the substrate material 110 at or aroundthe preheat temperature.

Referring to FIGS. 1-5, the preheated interval welding method 1 furthercomprises melting the weld material 120 in step 20 to produce moltenweld material 121. Specifically, melting the weld material 120 in step20 can comprise disposing the weld apparatus 130 adjacent the weldmaterial 120 in step 21 and heating the weld material 120 to atemperature above its liquidus temperature in step 22. In embodimentswhere the welding apparatus 130 comprises the preheating apparatus 140(such as when the same welding apparatus 130 is used to both preheat thesubstrate material 110 in step 10 and melt the weld material 120 in step20 as illustrated in FIGS. 2 and 3), then transitioning the preheatingapparatus 140 away from the substrate material 110 in step 13 maycorrespond with disposing the weld apparatus 130 adjacent the weldmaterial 120 as indicated by the dashed line connecting step 13 and step21 in FIG. 1. For example, transitioning the preheating apparatus 140away from the substrate material 110 in step 13 can be simultaneous withdisposing the weld apparatus 130 adjacent the weld material 120 in step21. Such an embodiment may reduce the amount of time between preheatingthe substrate material 110 in step 10 and melting the weld material 120in step 20 to limit the amount of temperature drop in the preheatedsubstrate material 110 before the molten weld material 121 is applied.

Melting the weld material 120 in step 20 may be accomplished utilizing avariety of welding apparatuses 130 as discussed above by applying heatand/or energy to the weld material 120 in step 22 to produce molten weldmaterial 121. For example, as illustrated in FIGS. 2 and 3, the weldingapparatus 130 can comprise an induction welding apparatus such that theweld material 120 can be heated to a temperature above its liquidustemperature via the induction coil 132. However, as also discussedabove, various other welding apparatuses 130 may alternatively beutilized to melt the weld material 120 in step 20 such as arc weldingapparatuses (e.g., TIG welding), gas welding apparatuses (e.g.,oxyacetylene welding), energy beam welding apparatuses (e.g., laser beamwelding) and/or any other alternative welding apparatuses capable ofheating the weld material 120 above its liquidus temperature.

Furthermore, melting the weld material 120 in step 20 may be performedin any type of environment. For example, in some embodiments, themelting of the weld material 120 in step 20 may occur in an inertatmosphere. In some embodiments, the melting of the weld material 120 instep 20 may occur in a low pressure environment. In some embodiments,the melting of the weld material 120 in step 20 may occur in any othertype of environment that allows for the melting of the weld material 120to produce molten weld material 121 for the subsequent application tothe substrate material 110 in a plurality of intervals.

In some embodiments, such as where the preheating apparatus 140 and thewelding apparatus 130 comprise the same apparatus (e.g., as illustratedin FIGS. 2 and 3), the melting of the weld material 120 in step 20 mayoccur at a melting distance D_(m). In some embodiments, the meltingdistance D_(m), from the substrate material 110 is great enough suchthat the welding apparatus 130 used to melt the weld material 120maintains the substrate material 110 below its solidus temperature. Insome embodiments, the melting distance D_(m) from the substrate material110 is greater than a preheating distance D_(ph) that separated thesubstrate material 110 from the welding apparatus 130 (or preheatingapparatus 140) when preheating the substrate material 110 in step 10. Byincreasing the distance (i.e., having a melting distance D_(m) greaterthan the preheating distance D_(ph)) the amount of heat and/or energyapplied to the substrate material 110 can be limited such that thetemperature of the substrate material 110 does not excessively rise,such as over its solidus temperature.

Still referring to FIGS. 1-3, the preheated interval welding method 1further comprises applying the molten weld material 121 in a pluralityof intervals to the substrate material 110 in step 30. Applying themolten weld material 121 in a plurality of intervals comprisesalternating the application of molten weld material 121 and breaks intime. For example, as illustrated in FIG. 1, applying the molten weldmaterial 121 in a plurality of intervals in step 30 can comprise a firstapplication of molten weld material 121 in step 31 (e.g., dropping afirst drop of molten weld material 121) followed by a first break instep 32 where no molten weld material 121 is applied. A secondapplication of molten weld material 121 can then occur in step 33 (e.g.,dropping a second drop of molten weld material 121) followed by a secondbreak in step 34 where no molten weld material 121 is applied. Thisalternating pattern may continue through the n^(th) application ofmolten weld material 121 as illustrated in step 35 (e.g., dropping then^(th) drop of molten weld material 121) wherein each application ofmolten weld material 121 (e.g., steps 31, 33 and 35) is separated by abreak (e.g., steps 32 and 34) when no molten weld material 121 isapplied.

In some embodiments, each application of molten weld material 121 (e.g.,steps 31, 33 and 35) may comprise substantially similar amounts ofmolten weld material 121 such that each application adds a morepredictable amount of molten weld material 121 to the substrate material110. Additionally, where melting the weld material 120 in step 20 occursin a specific environment (e.g., low pressure, in the presence of inertgasses, etc.), the application of molten weld material 121 in aplurality of intervals to the substrate material 110 in step 30 maysimilarly occur in the same or substantially similar environment.

It should now be appreciated that by preheating the substrate material110 to a preheat temperature approaching its liquidus temperature, thesubstrate material 110 can provide for an eventual metallurgical bondwith the weld material 120 with more similar microstructural andphysical properties, particularly when the weld material 120 matches thesubstrate material 110. Moreover, the preheated substrate material 110can also be preheated to a temperature approaching its solidustemperature such that when the molten weld material 121 is applied tothe substrate material 110 (e.g., when a drop of the molten weldmaterial 121 touches the substrate material 110), a small layer of thesubstrate material 110 may briefly rise to or above its solidustemperature where it is contact with the molten weld material 121. Suchan application may both provide a strong bond between the substratematerial 110 and the weld material 120 while also reducing the heataffected zone (“HAZ”) by limiting the amount of heat/energy applied tothe substrate material 110.

The terms “a” and “an” herein do not denote a limitation of quantity,but rather denote the presence of at least one of the referenced item.The modifier “about” used in connection with a quantity is inclusive ofthe stated value and has the meaning dictated by the context, (e.g.,includes the degree of error associated with measurement of theparticular quantity). The suffix “(s)” as used herein is intended toinclude both the singular and the plural of the term that it modifies,thereby including one or more of that term (e.g., the metal(s) includesone or more metals).

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. A preheated interval welding method for welding aweld material to a substrate material, the preheated interval weldingmethod comprising: preheating the substrate material to a preheattemperature less than a solidus temperature of the substrate material;melting the weld material to produce molten weld material at a meltingdistance away from the substrate material; and applying the molten weldmaterial in a plurality of intervals to the substrate material.
 2. Thepreheated interval welding method of claim 1, wherein the meltingdistance is great enough such that a welding apparatus used to melt theweld material maintains the substrate material below its solidustemperature.
 3. The preheated interval welding method of claim 1,wherein applying the molten weld material in a plurality of intervals tothe substrate material causes a portion of the substrate material totemporarily rise above its solidus temperature.
 4. The preheatedinterval welding method of claim 1, wherein applying the weld materialcomprises disposing liquid droplets of the molten weld material onto thesubstrate material.
 5. The preheated interval welding method of claim 1,wherein preheating the substrate material and melting the weld materialare performed using a single welding apparatus.
 6. The preheatedinterval welding method of claim 5, wherein the single welding apparatuscomprises an induction welding apparatus.
 7. The preheated intervalwelding method of claim 1, wherein preheating the substrate materialcomprises heating using an oven.
 8. The preheated interval weldingmethod of claim 1, wherein the substrate material comprises a nickelbased superalloy.
 9. A preheated interval welding method for welding aweld material to a substrate material, the preheated interval weldingmethod comprising: disposing a welding apparatus adjacent a substratematerial; preheating the substrate material to a preheat temperatureless than its solidus temperature; transitioning the welding apparatuselement away from the substrate material and adjacent to the weldmaterial; melting the weld material to produce molten weld material; andapplying the molten weld material in a plurality of intervals to thesubstrate material.
 10. The preheated interval welding method of claim9, wherein melting the weld material occurs at a distance away from thesubstrate material such that the welding apparatus maintains thesubstrate material below its solidus temperature.
 11. The preheatedinterval welding method of claim 10, wherein applying the molten weldmaterial in a plurality of intervals to the substrate material causes aportion of the substrate material to temporarily rise above its solidustemperature.
 12. The preheated interval welding method of claim 9,wherein the substrate material comprises a nickel based superalloy. 13.The preheated interval welding method of claim 9, wherein the preheattemperature of the substrate material is monitored by one or moretemperature sensors.
 14. The preheated interval welding method of claim13, wherein the one or more temperature sensors comprises at least apyrometer.
 15. A preheated interval welding system for preheating asubstrate material and applying a weld material, the preheated intervalwelding system comprising: a preheating apparatus that preheats a repairsurface of the substrate material to a preheat temperature; and awelding apparatus that melts the weld material into molten weld materialand applies the molten weld material to the repair surface in aplurality of intervals.
 16. The preheated interval welding system ofclaim 15, wherein the welding apparatus comprises the preheatingapparatus.
 17. The preheated interval welding system of claim 16,wherein the welding apparatus is at a preheating distance from thesubstrate material when preheating the substrate material and is at amelting distance from the substrate material that is greater than thepreheating distance when melting the weld material.
 18. The preheatedinterval welding system of claim 16, wherein the welding apparatuscomprises an induction welding apparatus.
 19. The preheated intervalwelding system of claim 15 further comprising one or more temperaturesensors to monitor the temperature of the substrate material.
 20. Thepreheated interval welding system of claim 19, wherein the preheatingapparatus preheats the substrate material to the preheat temperaturebased on feedback from the one or more temperature sensors.